Nearly all electronic and optical devices require patterning. Patterned metals are used in forming a variety of such devices. For example, patterned metals may be used in forming in transistors, as electrodes in various devices, and as shadow masks in the patterning of various materials.
One possible use for patterned metals is as electrodes in organic light emitting devices (OLEDs), which make use of thin films that emit light when excited by electric current. Popular OLED configurations include double heterostructure, single heterostructure, and single layer, and may be stacked, as described in U.S. Pat. No. 5,707,745, which is incorporated herein by reference in its entirety.
Patterned metals may be achieved by photoresist methods, as disclosed by U.S. Pat. No. 5,641,611 to Shieh, and in U.S. Pat. No. 6,013,538 to Burrows et al. Shadow masks may also be used to pattern various materials, as described in U.S. patent application Ser. No. 09/182,636. Shadow masks must be thick enough to provide mechanical strength and thus, the obtainable resolution of the pattern is limited. Other methods of patterning have been used, such as excimer laser ablation and conformal masks.
While these known patterning methods are acceptable in certain circumstances, as the patterning dimension decreases, the cost generally increases. Therefore, a more accurate, faster and less expensive method of patterning is desirable.